ProjectSummary Real-worldscenescontainfarmoreinformationthatwecanperceiveandcomprehendatanygivenmoment.A keymechanismformakingreal-worldsceneperceptiontractableisvisualattention?themechanismof preferentiallyprocessingonlypartofthesceneatanygiventime.Whatweattendtoinascenedetermines whatwesee,understand,andremember.Attentionisguidedbyboththevisualpropertiesofthesceneitself andbyourknowledgeaboutsimilarscenesandtheworldingeneral.Howknowledgeisusedtoguide attentionthroughameaningfulsceneremainslargelyunknown.Thecentralideabehindthisproposalisto addressthisfundamentalscientificquestionbyfocusingontwocriticalaspectsofsceneknowledge: knowledgeaboutwhereagivenobjectislikelytoappearinascene,andknowledgeaboutwhichregionsand objectsinascenearemeaningfulandinformative.Thestudiesaimtodeterminehowspatialandmeaning constraintsareusedtoguideattentioninscenes. Thisproposedresearchisinnovativeincombininghigh-resolutioneyetrackingwithnovelexperimental paradigmsformanipulatingandmeasuringknowledge-basedconstraints.First,anewfusionofspatiallearning methodswitheyetrackingisusedtostudytheinfluenceofspatialknowledgeonattentionalguidance.Second, newquantitativescene-ratingandinformation-theoreticmetricsareusedtoindexmeaninginscenes,providing anewtheoreticalapproachtoscenemeaningandnewempiricaltoolsforinvestigatingmeaning.Third,real- timescenemanipulationbasedontheviewer?seyemovementsiscombinedwithmanipulationsofspatialand meaningconstraintstoinvestigatehowquicklyknowledgeaboutascenebecomesavailabletoguideattention. Theprojectissignificantinchallengingcurrentmodelstoexplaintheroleofknowledgeinguidingattentionin scenes.Theexperimentsaredesignedtoadvancethefieldregardlessoftheoutcome,andwillproviderich andtheoreticallyconstrainingresultsthatmayhaveatransformativeeffectoncurrenttheory.Inaddition,the proposedresearchhasimportanttranslationalimplicationsbecausedeficitsinattentionandperceptionare sufferedbymanypsychiatricandneurologicalpopulations.Byunderstandinghowknowledgeinfluencesthe guidanceofattentioninrealscenes,theproposedstudiescanultimatelyleadtothedevelopmentoftargeted rehabilitationstrategiesfortherealworldthatbettercapitalizeonbothdisruptedandsparedfunctions.